TreeSet的简单使用

仅仅是使用方法，非源码分析。

public class Test {

    public static void main(String[] args) {
        TreeSet<String> treeSet=new TreeSet<>();
        treeSet.add("Se");
        treeSet.add("Ald");
        treeSet.add("Boo");
        treeSet.add("CC");
        Iterator<String> iterator=treeSet.iterator();
        while (iterator.hasNext()) {
            String string = (String) iterator.next();
            System.out.println(string);
        }
    }

}

输出：

Ald
Boo
CC
Se

使用TreeSet集合时，元素必须实现Comparable接口。

public class Person implements Comparable<Person> {
    private String name;
    private int age;

    public Person() {
        // TODO Auto-generated constructor stub
    }

    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        // TODO Auto-generated method stub
        return "name:" + getName() + "  age:" + getAge();
    }

    /**
     * 升序排列
     */
    @Override
    public int compareTo(Person person) {
        // TODO Auto-generated method stub
        if (this.getAge() > person.getAge()) {
            return 1;
        } else if (this.getAge() == person.getAge()) {
            return 0;
        } else {
            return -1;
        }
    }

}

测试类：

public class Test {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        TreeSet<Person> tSet = new TreeSet<>();
        tSet.add(new Person("shldom", 23));
        tSet.add(new Person("tom", 12));
        tSet.add(new Person("woa", 45));
        tSet.add(new Person("moe", 87));
        Iterator<Person> iterator=tSet.iterator();
        while(iterator.hasNext()){
            System.out.println(iterator.next());
        }
    }

}

输出结果：

name:tom  age:12
name:shldom  age:23
name:woa  age:45
name:moe  age:87